Brush holder for electric motors



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Patented Sept. 7, 1948 BRUSH HOLDER FOR ELECTRIC MOTORS Victor Weber, Greensburg, Pa.,

asslgnor to Robertshaw-Fulton Controls Company, a corporation of Delaware Application April 7, 1945, Serial No. 587,092

7 Claims. 1

This invention relates to electric motors and, more particularly, to brush holders therefor.

One object of the invention is to facilitate removal and replacement of the brush.

Another object of the invention is to lock the brush holder securely against displacement from its position of use.

Another object of the invention is to reduce the number of parts which must be'removed to obtain access to the brush.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing, wherein:

Fig. 1 is a. plan view of a portion of an electric motor housing showing the improved brush holder in position;

Fig. 2 is a cross-section through the motor housing portion and brush holder;

Fig. 3 is a section taken on the line 33 of Fig. 2.

Referring more particularly to the drawings, the portion of the electric motor housing A is shown as provided with a hollow boss B having the outer end portion of the inner wall C thereof provided with screw-threads D. The hollow boss B exposes a portion of a rotatable current conducting member E, such as a commutator, of the electric motor.

The improved brush holder comprises a sleeve I having one end projecting into the hollow boss B in spaced relation with the rotatable member E and the opposite end projecting beyond the housing A. Slidably mounted against rotation in the sleeve I is the brush 2 of the customary rectangular cross-section and which is supported for operative engagement with the rotatable member E. Beyond the end of the brush 2 the interior wall of the sleeve I is tapered in conical form and a retaining member 4 having a com-plementary taper producing a conical exterior wall is adapted to be maintained in friction-tight engagement therewith with a portion projecting therefrom. A coil spring 3 is mounted on the outer end of the brush 2 and extends through the conical portion of the sleeve I into engagement with the retaining member 4 which is suitably recessed for its reception.

A cap 5 is secured in the boss B by the screwthreads D and serves to enclose the retaining member 4 and the sleeve I. The cap 5 is provided with an enlarged annular recess 6 defining an interior shoulder therein located opposite the projecting end of the retaining member 4. Positioned within the recess 6 are an insulating plate l of the roove I2.

I and a curved spring plate 8. The insulating plate I is spaced from the wall of the recess 8 for loose mounting therein but is of sufficient area to require tilting to enable it to enter the recess 6 where it is retained by the shoulder therein. The curved spring plate 8 engages with the underside of the cap 5 and the insulating plate 1 and causes the latter to bear upon the projecting end of the retaining member 4 to prevent loosening of the same in the sleeve I. It is apparent that the spring .plate 8 is stronger than the coil spring 3 in order that the described function may be accomplished.

A spring clip 9 of U-shaped form has its terminal ends pivotally mounted in diametrically opposite apertures II in the cap 5. A shallow annular groove I2 is formed in the cap 5 intersecting the apertures II and engaging the terminal ends of the clip 9 to retain it in the plane of the groove I2. A pin III projects from the motor housing A and is adapted to be engaged by a portion of the spring clip 8 to prevent the cap 5 from becoming loose from the screw-threads D when the spring clip is retained in the plane However, in order that the cap 5 may be removed from the housing A when desired, the spring clip may be pivoted beyond such plane sufficiently to clear the end of the pin I0. It will be apparent. that during such pivotal movement of the spring clip 9, the terminal ends thereof will be forced outwardly relative to the apertures I I but will not become disengaged from the cap 5.

The sleeve I is supported against movement in the housing A by the provision of an insulating sleeve I3 having the outer wall thereof tightly engaged with the inner wall C of the boss B. The sleeve I is retained in the insulating sleeve I3 by knurling the engaging portion or otherwise sultably forming it for interlocking engagement. A terminal plate I4 is carried by the sleeve I and extends between the end of the insulating sleeve I3 and the current conducting member E. Preferably, the terminal plate I4 is provided with a pair of oppositely disposed upstanding lugs I6 engaging the sleeve I which may be suitably slotted for their reception. The lugs I6 provide convenient means for obtaining a good electrical connection between the sleeve I and terminal plate I4 by soldering or the like. The terminal plate I 4 is insulated from the motor housing A by the provision of an insulating disc I1 which is loosely interposed between the terminal plate I4 and the insulating sleeve I3 and extends beyond the boss B. The brush 2 and the retaining member 4 are electrically connected by a pigtail ll extending between the members.

The parts which require removal from the motor housing A to change the brush are the cap 5, spring plate 8, insulating plate I, retaining member 4, coil spring 3, pigtail l8 and brush 2. These parts may conveniently be assembled by inserting the brush 2 with its spring 3 within the sleeve l where it is held against rotation due to the complemental rectangular shape thereof.

The retaining member 4 carrying the pigtail I8 is then engaged in friction-tight relation with the sleeve l by manual pressure applied to the retaining member 4 serving to lock the conical parts together against the bias of the coil spring 3. The cap 5 carrying the curved spring plate 8 and insulating plate I is then threaded into the boss B of the motor housing A with the spring clip 9 in a tilted position to clear the pin III. Before the cap 5 is seated on the motor housing A the dished spring plate 8 is placed under compression due to the engagement of the insulating plate 1 with the projecting end of the retaining member 4. After the cap -5 is seated on the motor housing A the spring clip 9 is depressed into the plane of the groove l2 and will snap into position therein.

The disassembly of the brush holder from the motor housing A may be very easily accomplished by tilting the spring clip 9 out of the plane of the pin l and removing the cap completely. As previously noted, the insulatin plate I is retained in the enlarged recess 8 of the cap together with the dished spring plate 6 so that no separation occurs unless these two plates are intentionally tilted. The retaining member 4 together with the coil spring 3 and brush 2 may readily be withdrawn by manual pressure applied to the projecting end of the retaining member 4 or by the use of a common tool such as a screw driver.

The particular advantage of the improved brush holder will now be apparent in its ease of removal from and replacement in the motor housing. This feature is especially valuable in locations where space is limited necessitating that changes of brushes be accomplished by touch. As only a few of the necessary parts have to be removed and replaced, it is apparent that there is less danger that small components will become lost during the brush changing operation. There is, moreover, no danger that the brush and its spring will fly out of the assembl and become lost when the enclosing cap is removed.

It will be understood that many changes can be made in the arrangement and combination of parts and in the type of construction herein disclosed within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. In an electric motor having a housing and a rotatable current conducting member therein, the combination of a brush holder for supporting a brush in operative engagement with the rotatable member and comprising a brush-containing sleeve adapted to be secured in the housing with one end projecting in spaced relation with the rotatable member, yieldable means within said sleeve and extending from the brush toward the opposite end of said sleeve, a retaining member press-fitted in said opposite sleeve end and being maintained therein by mutual tight engagement therewith for exerting pressure on said yieldable means and thereby biasing the brush toward the rotatable member, a cap adapted to be detachably secured to the housing for enclosing said retaining member and sleeve, and means carried by said cap and bearing on said retaining member to prevent loosening of the same.

2. In an electric motor having a housing and a rotatable current conducting member therein, the combination of a brush holder for supporting a brush in operative engagement with the rotatable member and comprising a brush-containing sleeve adapted to be secured in the housing with one end projecting in spaced relation with the rotatable member, yieldable means within said sleeve and extending from the brush toward the opposite end of said sleeve, a retaining member press-fitted in said opposite sleeve end and being maintained therein by mutual frictiontight engagement therewith for exerting pressure on said yieldable means and thereby biasing the brush toward the rotatable member, a cap adapted to be detachably secured to the housing for enclosing said retainin member and sleeve, and means carried by said cap and yieldably bearing on said retaining member to prevent loosening of the same.

3. In an electric motor having a housing and a rotatable current conducting member therein, the combination of a brush holder for supporting a brush in operative engagement with the rotatable member and comprising a brush-containing sleeve adapted to be secured in the housing with one end projectin in spaced relation with the rotatable member, said sleeve having a tapered wall at the opposite end thereof, yieldable means within said sleeve and extending from the brush toward said opposite end of said sleeve, a retaining member having a tapered wall adapted to be maintained in friction-tight engagement with said tapered sleeve wall by press-fitted engagement between said member and sleeve, said member exerting pressure on said yieldable means and thereby biasing the brush toward the rotatable member, a cap adapted to be detachably secured to the housing for enclosing said retaining member and sleeve, and means carried by said cap and yieldably bearing on said retaining member to prevent loosening of the same.

4. In an electric motor having a housing and a rotatable current conducting member therein, the combination of a brush holder for supporting a brush in operative engagement with the rotatable member and comprising a brush-containing sleeve adapted to be secured in the housin with one end projecting in spaced relation with the rotatable member, said sleeve having a tapered wall at the opposite end thereofl yieldable means within said sleeve and extending from the brush toward said opposite end of said sleeve, a retaining member having a tapered wall maintained in friction-tight engagement with said tapered sleeve .eall for exerting pressure on said yieldable means and thereby biasing the brush toward the rotatable member, a cap adapted to be detachably secured to the housing for enclosing said retaining member and sleeve, said cap having an enlarged annular recess therein beyond said retaining member and defining an interior shoulder on said cap, an insulating plate loosely mounted in said recess and engageable with said shoulder for restraining separation from said sleeve, and a curved spring plate in said recess and operative between said cap and said insulating plate for causing the latter to bear upon said retaining member to prevent loosening of the same.

5. In an electric motor having a housing and a rotatable current conductin member therein, the combination of a brush holder for supporting a brush in operative engagement with the rotatable member and comprising a brush-containing sleeve adapted to be secured in the housing with one end projecting in spaced relation with the rotatable member, yieldable means within said sleeve and extending from the brush toward the opposite end of said sleeve, a retaining member press-fitted in said opposite sleeve end and being maintained therein by mutual tight engagement therewith for exerting pressure on said yieldable means and thereby biasing the brush toward the rotatable member, a cap threadedly engageable with the housing for enclosing said retaining member and sleeve, means carried by said cap and bearing on said retaining member to prevent loosening Of the same, and means pivotally mounted on said cap for movement into abutting relation with the housin to prevent loosening of said cap.

6. In an electric motor having a housing and a rotatable current conductin member therein, the combination of a brush holder for supporting a brush in operative engagement with the rotatable member and comprising a brush-containing sleeve adapted to be secured in the housing with one end projecting in spaced relation with the rotatable member, yieldable means within said sleeve and extending from the brush toward the opposite end of said sleeve, a retaining member pressfitted in said opposite sleeve and being maintained therein by mutual tight engagement therewith for exerting pressure on said yieldable means and thereby biasing the brush toward the rotatable member, a cap threadedly engageable with the housing for enclosing said retaining member and sleeve, means carried by said cap and bearing on said retaining member to prevent loosening of the same, and a sprin clip pivotally mounted on said cap for movement into abutting relation with the housing to prevent loosenin of said cap.

7. In an electric motor having a housing provided with a threaded aperture therein exposing the rotatable current conducting member, the combination of a brush holder for supporting a brush in operative engagement with the rotatable member and comprising a brush-containing sleeve having one end projecting into the aperture in spaced relation with the rotatable member, said sleeve having a tapered interior wall at the opposite end thereof, an insulating collar interposed between the wall of the aperture and said sleeve and having interlocking engagement with the latter, a coil spring within said sleeve and extending from the brush toward said opposite end of said sleeve, a retaining member having a tapered exterior wall maintained in friction-tight engagement with said tapered sleeve wall for exerting pressure on said spring and thereby biasing the brush toward the rotatable member, a flexible conductor between said retaining member and the brush, a cap threadedly engageable with the threaded aperture for enclosing said retainin member and sleeve, said cap having an enlarged annular recess therein beyond said retaining member and defining an interior shoulder on said cap, an insulating plate loosely mounted in said recess and engageable with said shoulder for restraining separation from said cap, a curved spring plate in said recess and operative between said cap and said insulating plate for causing the latter to bear upon said retaining member to prevent loosening of the same, and a spring clip pivotally mounted on said cap for movement into abutting relation with the housing to prevent loosening of said cap.

VICTOR WEBER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 

